linux-kernel - [PATCH 25/29] x86/perfcounters: return raw count with x86_perf_counter

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Message-ID: <1241002046-8832-26-git-send-email-robert.richter@amd.com>
Date:	Wed, 29 Apr 2009 12:47:22 +0200
From:	Robert Richter <robert.richter@....com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Robert Richter <robert.richter@....com>
Subject: [PATCH 25/29] x86/perfcounters: return raw count with x86_perf_counter_update()

To check on AMD cpus if a counter overflows, the upper bit of the raw
counter value must be checked. This value is already internally
available in x86_perf_counter_update(). Now, the value is returned so
that it can be used directly to check for overflows.

Signed-off-by: Robert Richter <robert.richter@....com>
---
 arch/x86/kernel/cpu/perf_counter.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index f4d59d4..a8a53ab 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -132,7 +132,7 @@ static u64 amd_pmu_raw_event(u64 event)
  * Can only be executed on the CPU where the counter is active.
  * Returns the delta events processed.
  */
-static void
+static u64
 x86_perf_counter_update(struct perf_counter *counter,
 			struct hw_perf_counter *hwc, int idx)
 {
@@ -165,6 +165,8 @@ again:
 
 	atomic64_add(delta, &counter->count);
 	atomic64_sub(delta, &hwc->period_left);
+
+	return new_raw_count;
 }
 
 static atomic_t num_counters;
@@ -785,8 +787,7 @@ static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi)
 			continue;
 		counter = cpuc->counters[idx];
 		hwc = &counter->hw;
-		x86_perf_counter_update(counter, hwc, idx);
-		val = atomic64_read(&hwc->prev_count);
+		val = x86_perf_counter_update(counter, hwc, idx);
 		if (val & (1ULL << (x86_pmu.counter_bits - 1)))
 			continue;
 		/* counter overflow */
-- 
1.6.1.3


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